using System;
using System.Collections.Generic;
using System.IO;
using System.Security.Cryptography;
using System.Text;

namespace Appointment.Entity
{
    public static class CryptoHelper
    {
        private static byte[] DESKeys = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };

        /// <summary>
        /// MD5小写加密
        /// </summary>
        /// <param name="token">加密前字符串</param>
        /// <returns></returns>
        /// <remarks>
        /// 使用了UTF8格式
        /// </remarks>
        public static string Md5(string token)
        {
            StringBuilder strHash = new StringBuilder();
            System.Security.Cryptography.MD5CryptoServiceProvider md5 = new System.Security.Cryptography.MD5CryptoServiceProvider();
            byte[] bytHash;

            bytHash = md5.ComputeHash(Encoding.UTF8.GetBytes(token));
            md5.Clear();
            for (int i = 0; i < bytHash.Length; i++)
            {
                strHash.Append(bytHash[i].ToString("x").PadLeft(2, '0'));
            }
            return strHash.ToString();
        }

        /// <summary>
        /// MD5大写加密
        /// </summary>
        /// <param name="input"></param>
        /// <returns></returns>
        /// <remarks>
        /// 字符串转为ASCII再加密 
        /// 与前面方法Md5()的区别是汉字加密后的结构不一致，
        /// </remarks>
        public static string Md5Hash(string input)
        {
            string strResult;
            using (var md51 = System.Security.Cryptography.MD5.Create())
            {
                var result = md51.ComputeHash(Encoding.ASCII.GetBytes(input));
                strResult = BitConverter.ToString(result);
                strResult = strResult.Replace("-", "");
            }
            return strResult;
        }

        /// <summary>
        /// DES加密字符串
        /// </summary>
        /// <param name="encryptString">待加密的字符串</param>
        /// <param name="encryptKey">加密密钥,要求为8位</param>
        /// <returns>加密成功返回加密后的字符串,失败返回源串</returns>
        public static string DES_Encode(string encryptString, string encryptKey = "dlhisapi")
        {
            encryptKey = encryptKey.Substring(0, 8);
            encryptKey = encryptKey.PadRight(8, ' ');
            byte[] rgbKey = Encoding.UTF8.GetBytes(encryptKey.Substring(0, 8));
            byte[] rgbIV = DESKeys;
            byte[] inputByteArray = Encoding.UTF8.GetBytes(encryptString);
            DESCryptoServiceProvider dCSP = new DESCryptoServiceProvider();
            MemoryStream mStream = new MemoryStream();
            CryptoStream cStream = new CryptoStream(mStream, dCSP.CreateEncryptor(rgbKey, rgbIV), CryptoStreamMode.Write);
            cStream.Write(inputByteArray, 0, inputByteArray.Length);
            cStream.FlushFinalBlock();
            return Convert.ToBase64String(mStream.ToArray());
        }

        /// <summary>
        /// DES解密字符串
        /// </summary>
        /// <param name="decryptString">待解密的字符串</param>
        /// <param name="decryptKey">解密密钥,要求为8位,和加密密钥相同</param>
        /// <returns>解密成功返回解密后的字符串,失败返源串</returns>
        public static string DES_Decode(string decryptString, string decryptKey = "dlhisapi")
        {
            try
            {
                decryptKey = decryptKey.Substring(0, 8);
                decryptKey = decryptKey.PadRight(8, ' ');
                byte[] rgbKey = Encoding.UTF8.GetBytes(decryptKey);
                byte[] rgbIV = DESKeys;
                byte[] inputByteArray = Convert.FromBase64String(decryptString);
                DESCryptoServiceProvider DCSP = new DESCryptoServiceProvider();

                MemoryStream mStream = new MemoryStream();
                CryptoStream cStream = new CryptoStream(mStream, DCSP.CreateDecryptor(rgbKey, rgbIV), CryptoStreamMode.Write);
                cStream.Write(inputByteArray, 0, inputByteArray.Length);
                cStream.FlushFinalBlock();
                return Encoding.UTF8.GetString(mStream.ToArray());
            }
            catch
            {
                return "";
            }
        }
    }


}